usb: gadget: uvc: configfs: ensure guid to be valid before set

When setting the guid via configfs it is possible to test if
its value is one of the kernel supported ones by calling
uvc_format_by_guid on it. If the result is NULL, we know the
guid is unsupported and can be ignored.
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Link: https://lore.kernel.org/r/20240221-uvc-gadget-configfs-guid-v1-1-f0678ca62ebb@pengutronix.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/function/uvc_configfs.c

@@ -13,6 +13,7 @@
 #include "uvc_configfs.h"
 
 #include <linux/sort.h>
+#include <linux/usb/uvc.h>
 #include <linux/usb/video.h>
 
 /* -----------------------------------------------------------------------------
@@ -2260,6 +2261,8 @@ static ssize_t uvcg_uncompressed_guid_format_store(struct config_item *item,
 	struct f_uvc_opts *opts;
 	struct config_item *opts_item;
 	struct mutex *su_mutex = &ch->fmt.group.cg_subsys->su_mutex;
+	const struct uvc_format_desc *format;
+	u8 tmpguidFormat[sizeof(ch->desc.guidFormat)];
 	int ret;
 
 	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
@@ -2273,7 +2276,16 @@ static ssize_t uvcg_uncompressed_guid_format_store(struct config_item *item,
 		goto end;
 	}
 
-	memcpy(ch->desc.guidFormat, page,
+	memcpy(tmpguidFormat, page,
+	       min(sizeof(tmpguidFormat), len));
+
+	format = uvc_format_by_guid(tmpguidFormat);
+	if (!format) {
+		ret = -EINVAL;
+		goto end;
+	}
+
+	memcpy(ch->desc.guidFormat, tmpguidFormat,
 	       min(sizeof(ch->desc.guidFormat), len));
 	ret = sizeof(ch->desc.guidFormat);